Messages in this thread | | | Date | Fri, 17 Jul 2020 14:51:42 +0200 | From | Frederic Weisbecker <> | Subject | Re: [PATCH 4/9] timers: Always keep track of next expiry |
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On Tue, Jul 14, 2020 at 10:49:28AM +0200, Anna-Maria Behnsen wrote: > Hi Frederic, > > On Tue, 7 Jul 2020, Frederic Weisbecker wrote: > > > So far next expiry was only tracked while the CPU was in nohz_idle mode > > in order to cope with missing ticks that can't increment the base->clk > > periodically anymore. > > > > We are going to expand that logic beyond nohz in order to spare timers > > softirqs so do it unconditionally. > > > > Signed-off-by: Frederic Weisbecker <frederic@kernel.org> > > Cc: Peter Zijlstra <peterz@infradead.org> > > Cc: Anna-Maria Gleixner <anna-maria@linutronix.de> > > Cc: Juri Lelli <juri.lelli@redhat.com> > > --- > > kernel/time/timer.c | 36 +++++++++++++++++++----------------- > > 1 file changed, 19 insertions(+), 17 deletions(-) > > > > diff --git a/kernel/time/timer.c b/kernel/time/timer.c > > index acf7cb8c09f8..8a4138e47aa4 100644 > > --- a/kernel/time/timer.c > > +++ b/kernel/time/timer.c > > @@ -558,8 +558,22 @@ trigger_dyntick_cpu(struct timer_base *base, struct timer_list *timer) > > * timer is not deferrable. If the other CPU is on the way to idle > > * then it can't set base->is_idle as we hold the base lock: > > */ > > - if (!base->is_idle) > > - return; > > + if (base->is_idle) > > + wake_up_nohz_cpu(base->cpu); > > +} > > + > > +/* > > + * Enqueue the timer into the hash bucket, mark it pending in > > + * the bitmap and store the index in the timer flags. > > + */ > > +static void enqueue_timer(struct timer_base *base, struct timer_list *timer, > > + unsigned int idx) > > +{ > > + hlist_add_head(&timer->entry, base->vectors + idx); > > + __set_bit(idx, base->pending_map); > > + timer_set_idx(timer, idx); > > + > > + trace_timer_start(timer, timer->expires, timer->flags); > > > > /* Check whether this is the new first expiring timer: */ > > if (time_after_eq(timer->expires, base->next_expiry)) > > @@ -578,21 +592,7 @@ trigger_dyntick_cpu(struct timer_base *base, struct timer_list *timer) > > } else { > > base->next_expiry = timer->expires; > > } > > - wake_up_nohz_cpu(base->cpu); > > -} > > > > -/* > > - * Enqueue the timer into the hash bucket, mark it pending in > > - * the bitmap and store the index in the timer flags. > > - */ > > -static void enqueue_timer(struct timer_base *base, struct timer_list *timer, > > - unsigned int idx) > > -{ > > - hlist_add_head(&timer->entry, base->vectors + idx); > > - __set_bit(idx, base->pending_map); > > - timer_set_idx(timer, idx); > > - > > - trace_timer_start(timer, timer->expires, timer->flags); > > trigger_dyntick_cpu(base, timer); > > } > > > > Could you please split those two hunks which do only a restructuring into a > separate patch?
The problem is that those hunks are not only a restructuring but they also change the way we update next_expiry, since we do it outside idle context. And that update won't make sense without the proper initialization of next_expiry that comes later in the patch.
Thanks.
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